BT-30 Ceramic Electrophysical Properties
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Vol. 61, No. 3, September, 2020
BT-30 CERAMIC ELECTROPHYSICAL PROPERTIES N. A. Drokin,1,2 V. S. Kiiko,3,5 A. V. Pavlov,4 and A. I. Malkin3 Translated from Novye Ogneupory, No. 6, pp. 56 – 63, June, 2020.
Original article submitted May 18, 2020. A total complex resistance (impedance) method is used to study the electrophysical characteristics of (BeO + TiO2)-ceramics modified with TiO2 micro- and nanoparticles in an amount of 30 wt.% (BT-30). Dispersion of the actual e¢ and imaginary e² components of the dielectric permittivity component and specific conductivity in the frequency range from 100 Hz to 100 MHz from room temperature to the boiling point of liquid nitrogen are determined. High values of e¢ and e² in the low-frequency range are typical for structurally inhomogeneous materials due to the accumulation of electric charges at the surface and within microcrystals. Two dielectric relaxation processes associated with electrical conductivity within the body and at the surface of ceramics are detected for the first time. An increase in conductivity with an increase in the microwave field frequency above 1 MHz is explained by the appearance of a current relaxation component. The activation energy of the static resistance of ceramic specimens is determined as a function of the reciprocal temperature that depends little on the weight content of TiO2 nanoparticles and varies in the range of 0.024 – 0.10 eV This also confirms the existence of two independent conduction processes, weakly dependent on the nanoparticle content in the ceramic composition. With placement of ceramic in a high-frequency electric field, spatial charges are formed, the field of which contributes to creation of additional polarization and dielectric losses. Keywords: (BeO + TiO2)-ceramic, electrophysical properties, electrical resistance activation energy.
UHF-ranges [2 – 8]. There is special interest in BeO ceramic with addition to its composition of an optimum amount of BT-30 TiO2 micro-powder (30 wt.%). Currently it is used in high power electronic engineering instruments as an absorbent material for dissipating UNF-radiation [2 – 8]. Physicochemical interpretation of the existence of a conducting space within the volume of (BeO – TiO2)-ceramic and at an electrode – conductor boundary, in which charge carriers are moved and localized, and also the nature of conductivity, are so far unclear [9]. Detailed representation about processes of electrical polarization and specific relaxation of spatial charges, which are capable of accumulating at boundaries of individual micro-crystals, does not exist. Work has been devoted to experimental study of the behavior of electrophysical properties of (BeO + TiO2)-ceramic modified with micro- and nano-particles of TiO2 with a change in temperature and frequency. Studies were conducted in the range from +25 to –194°C in the electric field frequency range 100 Hz – 100 MHz y measuring total complex resistance (Z – Z¢ – iZ² (impedance)) of a measurement cell prepared in the form of a flat condenser filled w
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